Underground cable terminations are primarily used in the power industry to transition from insulated underground cables to bare overhead conductors. Perhaps the most common type of termination is referred to as a cold shrink termination. A cold shrink termination typically consists of a molded elastomeric housing that is expanded and loaded onto a removable core. During field installation, the core and housing assembly is placed over a prepared cable and the core is removed, allowing the housing to shrink down to near its as-molded diameter creating an interference fit with the cable insulation.
One conventional termination includes a single, or constant, diameter elastomeric housing (one inside diameter throughout the length of the housing) that is loaded on or disposed over a dual diameter core as illustrated in FIGS. 1A and 1B. Loading the single, or constant, diameter elastomeric housing on the dual diameter core results in a portion of the elastomeric housing disposed over the larger diameter of the core being stretched far more than the portion of the elastomeric housing disposed over the smaller diameter of the core. As illustrated in FIGS. 1A and 1B, the single, or constant, diameter housing is shown bulging outward at one end indicating the stretching of the housing around the second larger diameter portion of the dual diameter core. Further, in said conventional termination, the portion of the housing disposed over the smaller diameter of the core is expanded significantly less than the elastomeric housing material's capability, thus restricting the ranges of cable that the termination can cover.
Another conventional termination illustrated in FIGS. 2A and 2B includes a single diameter core having a dual diameter housing (each part of the housing having a different inner diameter) that allows the termination to fit or cover a larger range of cables than compared to the termination with a dual diameter core and single diameter housing. To achieve the larger range of cables, the smaller inside diameter of the housing is expanded to near its maximum capability. Since the core is one straight diameter, this means that the larger inside diameter of the housing is not expanded very much, if at all. Since this portion of the housing is not significantly expanded, the housing (and the core beneath it) will not be able to slide over the larger diameter mastic and tape portion of the cable. As shown in FIG. 2A, the core must stop short and the larger diameter portion of the housing in this embodiment has to be folded back upon the smaller diameter housing portion. As a result, the installation of said conventional termination shown in FIG. 2B over a cable requires a user to perform numerous extra tedious steps. For example, as illustrated in FIG. 2B, the user will have to apply silicone lubricant to the cable and then pull down the folded up shed to tightly fit over the cable (or mastic ball around the cable). These additional steps may be time intensive, may increase the possibility of human error, and/or may be inconvenient to the user. Further, said additional step of pulling down the folded up shed over the lubricated cable may be tedious because the folded up shed may not be configured to provide a good grip to a user terminating the cable. This is further exacerbated by the silicone lubricant that may remain on the hands of the user from lubricating the cable.
The foregoing conventional cold shrink termination designs each have shortcomings. The examples in FIGS. 1A and 1B fully expand the elastomeric housing area that covers the larger mastic area of the cable to eliminate the extra installation steps, but sacrifices cable range taking ability because the main portion of the housing is not fully expanded. The prior art example in FIGS. 2A and 2B fully expands the main section of the housing that interfaces with the cable insulation to get optimal cable range taking ability, but does not fully expand the section of the housing that covers the cable mastic area, leading to a significantly more difficult and problematic field assembly.
Further, in conventional terminations, when the core and the housing assembly of the termination is placed over the prepared cable (e.g., cable with the mastic ball, the tape ball, etc., disposed over the outer diameter of the cable) for termination of the cable, the space/clearance between the outer diameter of the prepared cable and the inner diameter of the core of the termination may be limited. As a result, during field installation, when the core is removed to shrink or dispose the elastomeric housing over the prepared cable, portions of the core may engage the cable and get stuck requiring the termination to be cut and the termination process to be repeated with a new termination. This in turn results in a waste of the terminations and unnecessary delay which may be both time and cost intensive. Furthermore, the conventional terminations may not have good tracking resistance and dielectric breakdown resistance resulting in frequent deterioration requiring replacement of the conventional terminations. In other words, the conventional terminations may have a shorter life span and frequent replacements of the terminations may be cost, labor, and time intensive.
Accordingly, in light of the above mentioned shortcomings of the conventional terminations, there is a need for an improved termination.